Structurally dependent behavior of the nitromethyl group of aliphatic γ-nitrothioamides under nitrile oxide generation reaction conditions

Treatment of (3-allyl)-4-nitromethylthiolactams with phenyl isocyanate and triethylamine has been found to lead to (3-allyl)-4-isothiocyanatolactams. In the case of 3-unsubstituted 4-nitromethylthiolactams, the retro-Michael addition reaction of the nitromethyl group, affording α,β-unsaturated thiolactams and 4-nitromethyllactams, is also observed. Under the same reaction conditions acyclic (α-allyl)-γ-nitrothioamides have been unexpectedly found to lead to α,β-unsaturated nitriles. Mechanisms for these reactions are proposed.